Fourth Power raises $19 million for utility-scale thermal energy storage

Fourth Power secured $19 million in Series A funding led by DCVC to scale its carbon-block thermal battery and build a 1 MWh-e prototype near Boston by 2026. Long-duration storage advances like this are central to integrating variable wind and solar, a challenge directly relevant to India's renewable grid expansion.

Fourth Power raised $19 million in Series A funding to scale its thermal battery technology, led by venture capital firm DCVC with participation from Breakthrough Energy Ventures and Black Venture Capital Consortium. The funds will support its thermal energy storage solution and begin construction of a 1 MWh-e prototype facility near Boston, expected to complete in 2026. The system uses renewable electricity to heat carbon blocks via liquid tin, releasing stored heat as electricity through thermophotovoltaic cells when needed.

The development affects grid operators and the long-duration storage sector. Fourth Power's modular, scalable system can store energy for over a month and discharge over periods from hours to days at minimal cost, giving operators flexibility to manage variable wind and solar generation and ensure reliable 24/7 supply. The technology, conceived by Dr. Asegun Henry at Georgia Tech and now associated with MIT, holds records including 41% thermophotovoltaic efficiency and a Guinness World Record for the highest-temperature pump.

Grid planners and storage developers should monitor the 1 MWh-e prototype targeted for completion in 2026, alongside durability testing and engineering team expansion the funding will support. Indian utilities and renewable developers facing curtailment of wind and solar can track whether such long-duration thermal storage proves cost-competitive at utility scale. The system's ability to store energy that would otherwise be wasted during curtailment is a metric worth watching as renewable penetration grows.

Key figure — Series A funding raised: $19 million led by DCVC